Pyridinium iodides and process of preparing them



Patented May 7, 1935 PATENT OFFICE PYRIDINIUM IODIDESAND PROCESS OF 1 PREPARING THEM Leslie G. S. Brooker, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New York No Drawing. Original application January 16,

1933, Serial No. 652,030. Divided and this application November 7, 1933, Serial No. 697,067

6 Claims.

This invention relates to intermediates used in the preparation of cyanine dyes of the tricarbocyanine series. These intermediates may be termed (2-quinolyl alkyl iodide) -pyridinium 5 iodides and (Z-pyridyl alkyl iodidel-pyridinium iodides. This application is a division of my copending application Serial No. 652,030 filed January 16, 1933.

It is an object of my invention, therefore, to

provide these new dye intermediates and a method of preparing them.

In general, the method of preparing these intermediates is as follows: Equimolecular proportions of 2-iodoquinoline alkyl iodides and pyridine are caused to combine to give intermediate compounds of a new type, probably represented by the following formula-- N R/N\I (Z-quinolyl alkyl iodide)-pyridinium iodide These intermediate compounds can be isolated by treating the finely pulverized 2-iodoquino1ine alkyl iodides with pyridine, preferably in the cold, for 12 to 24 hours, and are then obtained as orange colored solids which can be purified by very rapid recrystallization from water. It is convenient to employ a large excess of pyridine in the reaction. The new compounds are unstable towards recrystallization butare quite soluble in hot water, whereas the 2-iodoquinoline alkyl iodides are only sparingly soluble. (2- quinolyl methiodide)-pyridinium iodide is obtained as orange-ochre crystals on recrystallization from water and melts at I'm-171 C. (with decomp.) (corn)- The corresponding ethiodide melts at 167-168 (with decomp.) (corn).

The Z-iodopyridine alkyl iodides, in a similar fashion, give rise to the compounds probably possessing the structural formula R=alkyl (2-pyrldy1 alkyl mamo-pyr dmmm iodide These compounds are yellow solids and are recrystallized in the same manner as described in the previous paragraph.

While the methyl and ethyl groups are the alkyl radicals which I commonly employ in the alkyl iodides used as startingmaterials, it is obvious that I may employ any of the other alkyl radicals commonly known to those skilled in the art.

What I claim as my invention and. desire to be secured by Letters Patent of the United States is: g

1. (Z-quinolyl alkyl iodide) -pyridinium iodide.

2. (2-pyridyl alkyl iodide) -pyridinium iodide.

3. The process which comprises-condensing pyridine with a compound of the following structure:

wherein R represents an alkyl group and B represents a substituent selected from the group consisting of vinylene and phenylene.

4. The process which comprises condensing pyridine with a 2-iodopyridine alkyl iodide.

5. The process which comprises condensing pyridine with a 2-iodoquinoline alkyl iodide.

6. A quaternary salt of the following structure:

l R- A LESLIE G. s. BROOKER. 

